From 7c37c79510329cd951a4dedf3f7bf7e2b18dccec Mon Sep 17 00:00:00 2001 From: Chao Yu Date: Mon, 20 Oct 2025 10:42:12 +0800 Subject: [PATCH] f2fs: fix to avoid updating zero-sized extent in extent cache As syzbot reported: F2FS-fs (loop0): __update_extent_tree_range: extent len is zero, type: 0, extent [0, 0, 0], age [0, 0] ------------[ cut here ]------------ kernel BUG at fs/f2fs/extent_cache.c:678! Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI CPU: 0 UID: 0 PID: 5336 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 RIP: 0010:__update_extent_tree_range+0x13bc/0x1500 fs/f2fs/extent_cache.c:678 Call Trace: f2fs_update_read_extent_cache_range+0x192/0x3e0 fs/f2fs/extent_cache.c:1085 f2fs_do_zero_range fs/f2fs/file.c:1657 [inline] f2fs_zero_range+0x10c1/0x1580 fs/f2fs/file.c:1737 f2fs_fallocate+0x583/0x990 fs/f2fs/file.c:2030 vfs_fallocate+0x669/0x7e0 fs/open.c:342 ioctl_preallocate fs/ioctl.c:289 [inline] file_ioctl+0x611/0x780 fs/ioctl.c:-1 do_vfs_ioctl+0xb33/0x1430 fs/ioctl.c:576 __do_sys_ioctl fs/ioctl.c:595 [inline] __se_sys_ioctl+0x82/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f07bc58eec9 In error path of f2fs_zero_range(), it may add a zero-sized extent into extent cache, it should be avoided. Fixes: 6e9619499f53 ("f2fs: support in batch fzero in dnode page") Cc: stable@kernel.org Reported-by: syzbot+24124df3170c3638b35f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-f2fs-devel/68e5d698.050a0220.256323.0032.GAE@google.com Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim --- fs/f2fs/file.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index ffa045b39c01d..c045e38e60ee8 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -1654,8 +1654,11 @@ static int f2fs_do_zero_range(struct dnode_of_data *dn, pgoff_t start, f2fs_set_data_blkaddr(dn, NEW_ADDR); } - f2fs_update_read_extent_cache_range(dn, start, 0, index - start); - f2fs_update_age_extent_cache_range(dn, start, index - start); + if (index > start) { + f2fs_update_read_extent_cache_range(dn, start, 0, + index - start); + f2fs_update_age_extent_cache_range(dn, start, index - start); + } return ret; } -- 2.47.3